1. Field of the Invention
The present invention relates to the field of computer graphics and, in particular, to perceptual detail and acutance enhancement for digital images.
2. Description of the Related Art
Digital videos and/or digital images are typically associated with a particular encoding technique and/or a particular resolution. However, the quality of the digital video and/or digital image can be visually compromised as a result of poor encoding or poor video resolution. Poor video quality distracts viewers from the content and negatively impacts the viewer experience. In particular, the human eye is very sensitive to repeating patterns or geometric patterns introduced with many encoding techniques. Artifacts from high compression, low bitrates, among others, decrease visual detail and acutance. Acutance is typically related to edge contrast in a video or image. Encoding and compression also creates posterization or “flat” spots in imagery that includes smooth gradients or details with very similar shades and colors.
In addition, digital videos and/or digital images are often displayed at resolutions greater than their native resolution. For example, a small video can be played back at “full screen” resolution. Bicubic or bilinear upscaling can be used to fill in missing pixels at the higher resolution, but the “smoothing” effect introduced by these techniques causes significant blurriness, both actual and perceived. Increasing contrast, or sharpening images, to compensate for the blurriness associated with upscaling exacerbates the video degradation and brings the artifacts themselves into sharper focus. Sharpening can also create additional visual artifacts.
As the foregoing illustrates, there is a need in the art for a technique that increases perceived image quality and reduces appearance of encoding artifacts in digital videos and/or digital images.